1. Field of the Invention
This invention relates to directing light at an angle. The invention is particularly useful for directing laser light with optical fibers at an angle to the fibers' axis inside a patient for medical examination and treatment.
2. Description of the Prior Art
Hashimoto, D. et al., "A Lateral Radiation Probe in YAG Laser Therapy," published in Gastrointestinal Endoscopy disclose a probe for applying uniform radiation refracted at a right angle from a quartz fiber with a 1 -mm sized microprism. The probe disadvantageously depends on the precise attachment and alignment of the microprism to the quartz fiber to refract light.
Beasley, J. D. U.S. Pat. No. 4,725,115 issued on Feb. 16, 1988 discloses a multi-mode optical fiber laser coupler with a spherical microlens which focuses light from a solid state laser onto a partially reflecting mirror. The mirror is formed by polishing the ends of two fibers at 45 degrees and assembling them such that the ends abut and are substantially parallel. The disclosed apparatus disadvantageously requires the use of delicate and accurately aligned mirrors to direct laser light.
There is a need therefore for a relatively simple and robust device for directing light at an angle from a straight length of optical fibers.